Anna Kock

Autocrine Prostaglandin E2 Signaling Promotes Tumor Cell Survival and Proliferation in Childhood Neuroblastoma

Background Prostaglandin E2 (PGE2) is an important mediator in tumor-promoting inflammation. High expression of cyclooxygenase-2 (COX-2) has been detected in the embryonic childhood tumor neuroblastoma, and treatment with COX inhibitors significantly reduces tumor growth. Here, we have investigated the significance of a high COX-2 expression in neuroblastoma by analysis of PGE2 production, the expression pattern and localization of PGE2 receptors and intracellular signal transduction pathways activated by PGE2. Principal Findings A high expression of the PGE2 receptors, EP1, EP2, EP3 and EP4 in primary neuroblastomas, independent of biological and clinical characteristics, was detected using immunohistochemistry. In addition, mRNA and protein corresponding to each of the receptors were detected in neuroblastoma cell lines. Immunofluorescent staining revealed localization of the receptors to the cellular membrane, in the cytoplasm, and in the nuclear compartment. Neuroblastoma cells produced PGE2 and stimulation of serum-starved neuroblastoma cells with PGE2 increased the intracellular concentration of calcium and cyclic AMP with subsequent phosphorylation of Akt. Addition of 16,16-dimethyl PGE2 (dmPGE2) increased cell viability in a time, dose- and cell line-dependent manner. Treatment of neuroblastoma cells with a COX-2 inhibitor resulted in a diminished cell growth and viability that was reversed by the addition of dmPGE2. Similarly, PGE2 receptor antagonists caused a decrease in neuroblastoma cell viability in a dose-dependent manner. Conclusions These findings demonstrate that PGE2 acts as an autocrine and/or paracrine survival factor for neuroblastoma cells. Hence, specific targeting of PGE2 signaling provides a novel strategy for the treatment of childhood neuroblastoma through the inhibition of important mediators of tumor-promoting inflammation.

COX/mPGES-1/PGE2 pathway depicts an inflammatory-dependent high-risk neuroblastoma subset.

Significance Cancer-related inflammation promotes progression and therapy resistance in tumors of adulthood. Knowledge concerning the significance of inflammation in childhood malignancies has been limited. Neuroblastoma is an embryonal tumor of early childhood with poor prognosis despite intensified therapy, and biological understanding is necessary to develop novel therapies. We found high-risk neuroblastoma, in particular the therapy-resistant subset with chromosome 11q-deletion, to be inflammatory driven and characterized by high expression of the COX/microsomal prostaglandin E synthase-1 (mPGES-1)/prostaglandin E2 (PGE2) pathway that correlates with metastatic stage and poor clinical outcome. We further detected infiltrating cancer-associated fibroblasts expressing mPGES-1, the essential enzyme for synthesis of PGE2, promoting tumor growth, angiogenesis, and metastatic spread. Treatment targeting this inflammatory pathway provides a therapeutic option for neuroblastoma and other cancers. The majority of solid tumors are presented with an inflammatory microenvironment. Proinflammatory lipid mediators including prostaglandin E2 (PGE2) contribute to the establishment of inflammation and have been linked to tumor growth and aggressiveness. Here we show that high-risk neuroblastoma with deletion of chromosome 11q represents an inflammatory subset of neuroblastomas. Analysis of enzymes involved in the production of proinflammatory lipid mediators showed that 11q-deleted neuroblastoma tumors express high levels of microsomal prostaglandin E synthase-1 (mPGES-1) and elevated levels of PGE2. High mPGES-1 expression also corresponded to poor survival of neuroblastoma patients. Investigation of the tumor microenvironment showed high infiltration of tumor-promoting macrophages with high expression of the M2-polarization markers CD163 and CD206. mPGES-1–expressing cells in tumors from different subtypes of neuroblastoma showed differential expression of one or several cancer-associated fibroblast markers such as vimentin, fibroblast activation protein α, α smooth muscle actin, and PDGF receptor β. Importantly, inhibition of PGE2 production with diclofenac, a nonselective COX inhibitor, resulted in reduced tumor growth in an in vivo model of 11q-deleted neuroblastoma. Collectively, these results suggest that PGE2 is involved in the tumor microenvironment of specific neuroblastoma subgroups and indicate that therapeutic strategies using existing anti-inflammatory drugs in combination with current treatment should be considered for certain neuroblastomas.

Neuroblast differentiation during development and in neuroblastoma requires KIF1Bβ-mediated transport of TRKA

We recently identified pathogenic KIF1Bβ mutations in sympathetic nervous system malignancies that are defective in developmental apoptosis. Here we deleted KIF1Bβ in the mouse sympathetic nervous system and observed impaired sympathetic nervous function and misexpression of genes required for sympathoadrenal lineage differentiation. We discovered that KIF1Bβ is required for nerve growth factor (NGF)-dependent neuronal differentiation through anterograde transport of the NGF receptor TRKA. Moreover, pathogenic KIF1Bβ mutations identified in neuroblastoma impair TRKA transport. Expression of neuronal differentiation markers is ablated in both KIF1Bβ-deficient mouse neuroblasts and human neuroblastomas that lack KIF1Bβ. Transcriptomic analyses show that unfavorable neuroblastomas resemble mouse sympathetic neuroblasts lacking KIF1Bβ independent of MYCN amplification and the loss of genes neighboring KIF1B on chromosome 1p36. Thus, defective precursor cell differentiation, a common trait of aggressive childhood malignancies, is a pathogenic effect of KIF1Bβ loss in neuroblastomas. Furthermore, neuropathy-associated KIF1Bβ mutations impede cargo transport, providing a direct link between neuroblastomas and neurodegeneration.

Inhibition of Microsomal Prostaglandin E Synthase-1 in Cancer-Associated Fibroblasts Suppresses Neuroblastoma Tumor Growth

Despite recent progress in diagnosis and treatment, survival for children with high-risk metastatic neuroblastoma is still poor. Prostaglandin E2 (PGE2)-driven inflammation promotes tumor growth, immune suppression, angiogenesis and resistance to established cancer therapies. In neuroblastoma, cancer-associated fibroblasts (CAFs) residing in the tumor microenvironment are the primary source of PGE2. However, clinical targeting of PGE2 with current non-steroidal anti-inflammatory drugs or cyclooxygenase inhibitors has been limited due to risk of adverse side effects. By specifically targeting microsomal prostaglandin E synthase-1 (mPGES-1) activity with a small molecule inhibitor we could block CAF-derived PGE2 production leading to reduced tumor growth, impaired angiogenesis, inhibited CAF migration and infiltration, reduced tumor cell proliferation and a favorable shift in the M1/M2 macrophage ratio. In this study, we provide proof-of-principle of the benefits of targeting mPGES-1 in neuroblastoma, applicable to a wide variety of tumors. This non-toxic single drug treatment targeting infiltrating stromal cells opens up for combination treatment options with established cancer therapies.

Abstract 687: Targeting tumor-promoting neuroblastoma microenvironment: inhibiton of tumor development and progression by targeting mPGES-1 expressed by cancer associated fibroblasts

Background: High-risk neuroblastomas present a tumor promoting microenvironment with infiltrating cancer associated fibroblasts (CAFs) expressing the mPGES-1 enzyme, essential for prostaglandin E2 (PGE 2 ) synthesis regulating tumor inflammation and immune suppression, angiogenesis, genetic instability, tumor progression and therapy resistance. We investigated the impact of novel therapy targeting the COX/mPGES-1/PGE 2 pathway. Methods: Human neuroblastomas were investigated for immunosuppressive microenvironment and expression of the COX/mPGES-1/PGE 2 /EP-receptor pathway. High-risk in vivo models, human 11q-deleted xenografts and transgenic MYCN-driven tumors, were treated with a novel specific mPGES-1 inhibitor. Tumor-fibroblast co-cultures examined cell migration. Inflammatory lipid mediators were analyzed by LC-MS/MS. Tumor tissues were analyzed by immunohistochemistry, immunofluorescence and FACS. Results: Tumor microenvironment in human high-risk neuroblastomas and both 11q-deleted xenografts and MYCN-driven transgenic mice displayed mPGES-1 expression in PDGFRb+ cancer associated fibroblasts. MPGES-1 expression correlated with high-risk neuroblastoma prognosis and infiltration of tumor-promoting macrophages with M2-polarization markers CD163 and CD206. The inflammatory regulator STAT3 was active in mPGES-1 expressing CAFs. Expression of the inflammatory COX/mPGES-1/PGE 2 /EP-receptor pathway in experimental tumors resembled high-risk primary human neuroblastomas. Targeting mPGES-1 with a novel compound decreased PGE 2 , induced M1 polarization of macrophages, decreased cancer associated fibroblasts and reduced angiogenesis significantly in treated tumors. Tumor development in the xenograft model was delayed and growth of established xenografts and transgenic tumors was significantly decreased by non-toxic treatment in vivo when compared to neuroblastoma tumors in untreated animals. Tumor cell stimulated CAF migration and infiltration was inhibited by targeting mPGES-1. Conclusions: Tumor-promoting inflammation and suppression of anti-tumor immunity in neuroblastoma is mediated through prostaglandin E 2 and STAT3 expression in cancer associated fibroblasts in the tumor microenvironment. Early targeting of mPGES-1 may inhibit CAF infiltration and tumor development. This novel tumor treatment targeting mPGES-1 decreases inflammatory mediators, modulates tumor-promoting microenvironment and inhibits significantly aggressive tumor growth and progression. We conclude that treatment targeting non-malignant cells in the neuroblastoma microenvironment may constitute a novel clinical therapeutic approach. Citation Format: Anna Kock, Karin Larsson, Nina Eissler, Filip Bergqvist, Joan Rauf, Marina Korotkova, John-Inge Johnsen, Per-Johan Jakobsson, Per Kogner. Targeting tumor-promoting neuroblastoma microenvironment: inhibiton of tumor development and progression by targeting mPGES-1 expressed by cancer associated fibroblasts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 687. doi:10.1158/1538-7445.AM2017-687

Abstract 761: Specific inhibition of prostaglandin E2 production in medulloblastoma

Introduction: Prostaglandin E2 (PGE2) is a key lipid mediator of inflammation and carcinogenesis. Apart from promoting direct growth of cancer cells, PGE2 has been shown to be crucial in maintaining the immunosuppressive tumor microenvironment. Drugs targeting cyclooxygenase (COX)-1 and -2, enzymes upstream in the production of PGE2 and other prostanoids, have successfully reduced tumor growth in many cancer models but these drugs are all associated with adverse long-term effects. The aim of this study is to demonstrate an anti-tumor effect in medulloblastoma by selective inhibition of microsomal prostaglandin E1 (mPGES-1), the enzyme downstream of COX-1/2 specifically required for the synthesis of PGE2. Experimental procedures: Human medulloblastoma cell lines (DAOY and D283) were treated with a selective small-molecule inhibitor against mPGES-1 or COX-2 in the presence or absence of pro-inflammatory interleukin (IL)-1â. Prostaglandins in supernatants were extracted and quantified with LC-MS/MS. Drug efficacy was determined and cell toxicity was measured with cell viability assay. Mice with human medulloblastoma xenograft will function as proof-of-concept for the anti-tumor activities associated with inhibition of PGE2 production. Key inflammatory enzymes were quantified with Western blot. Results: Medulloblastoma cells express high levels of COX-2, mPGES-1, and produce PGE2. The increased production of PGE2 by IL-1â was completely blocked when cells were co-treated with inhibitor for mPGES-1 or COX-2. Both inhibitors showed cell toxicity. We did not observe any shunting towards other prostanoids. Conclusion: We investigate the effect of selective inhibition of mPGES-1 or COX-2 on medulloblastoma growth. We aim to further characterize the mPGES-1 inhibitor and compare to selective COX-2 inhibitor in preclinical medulloblastoma models. Specific inhibition of PGE2 production, rather than general inhibition of prostanoid production, would potentially prove useful as a complement to current medulloblastoma treatments. Citation Format: Filip Bergqvist, Linda Ljungblad, Malin Wickstrom, Karin Larsson, Anna Kock, Marina Korotkova, John Inge Johnsen, Per Kogner, Per-Johan Jakobsson. Specific inhibition of prostaglandin E2 production in medulloblastoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 761.

Immune suppression by myeloid-derived suppressor cells, MDSCs, in MYCN-driven neuroblastoma provides a potential target for cancer immunotherapy.

Background Novel developments in tumor-immunotherapy show promising results in cancer therapy and might provide new opportunities for neuroblastoma treatment. To define suitable immunological targets, it is crucial to understand the role of the immune system and the mechanisms underlying neuroblastoma-induced immune suppression. We previously demonstrated accumulation of pro-inflammatory immune cells within tumor tissues and effective antiinflammatory treatment with low-dose aspirin in the TH-MYCN mouse model. This model can be further used to dissect detailed mechanisms of neuroblastoma-induced immune suppression relevant for tumor development and tumor progression with the overall aim to define suitable targets for neuroblastoma immunotherapy. Methods

Abstract 3986: Characterization of prostaglandin signaling in primary neuroblastoma

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Neuroblastoma (NB) is an embryonic childhood tumor of the sympathetic nervous system. Despite intensive treatment patients in the high-risk group of NB shows a poor prognosis. We have shown the importance of inflammation in NB development and progression and that the pro-inflammatory lipid mediator prostaglandin E2 (PGE2) acts as a paracrine survival factor in NB. We have also shown that mPGES-1, essential for PGE2 synthesis, promotes growth and survival of several malignancies. In this study we focus on the abundance of prostaglandins and their specific enzymes in primary NB of different biological and clinical subsets in the aim of finding a more specific and targeted NB treatment. Levels of prostaglandins were assayed in 40 primary human NB tumors by mass spectrometry (MS) showing elevated levels of PGE2 in high risk 11q-deleted NB compared to low-risk NB whereas elevated levels of prostaglandin D2 (PGD2) could be coupled to NB with favorable clinical outcome. The expression of COX-1, COX-2, mPGES-1, L-PGDS, H-PGDS and 15-PGDH were analyzed in tumors by immunohistochemistry (IHC). Expression of mPGES-1 and L-PGDS was found in all analyzed tumors. Double stainings of mPGES-1 and the specific NB cell marker GD2 were performed on tumors with different biology using immunofluorescence. In low-risk tumors mPGES-1 is not expressed by the tumor cells whereas co-localization were found in 11q deleted high-risk tumors. To consider the level of inflammation and PGE2 signaling in these tumors we analyzed cell markers of both the innate and adaptive immune system together with mPGES-1. In all tumors mPGES-1 expressing cells are found in clusters closely together with T-cells, B-cells, dendritic cells and M1/M2 macrophages. Together this suggests an involvement of inflammatory prostaglandins in neuroblastoma development and tumor progression opening up new strategies for targeted therapies. Citation Format: Anna Kock, Karin Larsson, Linda Ljungblad, Helena Idborg, Marina Korotkova, Lotta Elfman, John-Inge Johnsen, Per-Johan Jakobsson, Per Kogner. Characterization of prostaglandin signaling in primary neuroblastoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3986. doi:10.1158/1538-7445.AM2014-3986

Abstract 2746: Microsomal prostaglandin E2 synthase-1 may provide a novel specific therapeutic target in neuroblastoma.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Background: Neuroblastoma (NB) cells are enriched in the omega-6 fatty acid arachidonic acid, the substrate for the cyclooxygenase (COX) enzymes and prostaglandin biosynthesis. The inducible isoform, COX-2 is overexpressed in NB and NB cells produce prostaglandin E2 (PGE2) that acts as an autocrine and/or paracrine survival and proliferation factor. Downstream of the COX enzymes, specific synthases are responsible for the production of the respective prostaglandins. Microsomal prostaglandin E2 synthase-1 (mPGES-1) specifically converts PGH2 to PGE2 and is thought to primarily couple to COX-2. The aim of this study was to investigate if inhibition of mPGES-1 could represent an alternative therapeutic approach to COX- inhibition in NB. Methods: Western blot and immunohistochemistry were used for protein detection. Cell viability of seven NB cell-lines treated with the mPGES-1 inhibitor CAY1052 was determined by MTT-assay. Stable mPGES-1 knockdown SK-N-BE2 clones were established using shRNA and the clonogenic capacity was analysed by clonogenic assay. To study the in vivo effect of COX inhibition, four week old homozygous TH-MYCN mice were treated with 10mg/L diclofenac for two weeks. Ex vivo analyses of COX-metabolites in tumors were performed by LC-MS/MS. Results: Expression of mPGES-1 in human NB tumors and in NB cell lines could be detected. Inhibition of mPGES-1 reduced NB cell growth in vitro and knockdown of mPGES-1 significantly reduced the clonogenic capacity. Expression of COX-1, COX-2 and mPGES-1 in TH-MYCN tumors could be detected and treatment with the dual COX-inhibitor diclofenac significantly reduced tumour weight, compared to untreated animals. Ex vivo analysis of tumor tissues from treated animals revealed a significantly decreased level of COX metabolites compared to controls. The expression of mPGES-1was not affected by the treatment. Furthermore, cells staining positive for cleaved caspase-3 were more prevalent in treated tumors indicating apoptosis Induction. Conclusion: We found that mPGES-1 is expressed in NB, with a potential role for PGE2 synthesis and tumor growth. mPGES-1 represents an alternative therapeutic target for inhibiting NB growth through specific PGE2 inhibition and the TH-MYCN model is well suited for in vivo studies with this purpose. Citation Format: Anna Kock, Agnes Rasmuson, Marina Korotkova, Helena Idborg, John Inge Johnsen, Per-Johan Jakobsson, Per Kogner. Microsomal prostaglandin E2 synthase-1 may provide a novel specific therapeutic target in neuroblastoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2746. doi:10.1158/1538-7445.AM2013-2746

Abstract 1420: Microsomal prostaglandin E2 synthase 1 (mPGES-1) is expressed in neuroblastoma and may represent a novel target for therapy

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Neuroblastoma (NB) is an embryonic tumor of the sympathetic nervous system and it is the most common extracranial tumor affecting young children. Despite a very intensive treatment regimen high-risk neuroblastoma patients still have a poor prognosis. Neuroblastoma cells are enriched in arachidonic acid, over express COX-2 and produce prostaglandin E2 (PGE2) that acts as an autocrine or paracrine survival and proliferation factor by induction of Akt signaling. Downstream of the COX enzymes, specific synthases converts PGH2 into the different prostaglandins. Microsomal prostaglandin E2 synthase-1 (mPGES-1) specifically converts PGH2 to PGE2 and is thought to primarily couple to COX-2. The aim of this study is to investigate if inhibition of mPGES-1 could represent an alternative therapeutic approach to COX- inhibition in neuroblastoma. We could detect expression of mPGES-1 in a panel of seven human neuroblastoma cell lines. Stable knock down of mPGES-1 expression using shRNA significantly reduced the clonogenic capacity and treatment with the mPGES-1 inhibitor CAY1052 inhibited neuroblastoma cell growth in vitro. By immunohistochemistry and western blot we could also detect expression of COX-1, COX-2 and mPGES-1 in tumors from the transgenic TH-MYCN mouse model of neuroblastoma. Treatment of homozygous TH-MYCN mice with 10 mg/L diclofenac for two weeks, starting at the age of four weeks, significantly reduced tumour weight compared to untreated animals. Ex vivo analysis with LC-MS/MS of tumor tissues from diclofenac treated animals revealed a significant decreased level of COX metabolites compared to control. The expression of mPGES-1was not affected by the treatment. Furthermore the number of cells staining positive for cleaved caspase-3 were higher in the treated tumors indicating induced apoptosis. In conclusion, our results show that mPGES-1 is expressed in neuroblastoma therefore mPGES-1 might represent an alternative way of reducing NB growth through specific PGE2 inhibition. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1420. doi:1538-7445.AM2012-1420